The correct answer is: D. Nasiruddin Mahmud
Nasiruddin Mahmud was the third Sultan of the Mamluk dynasty of Delhi. He was the son of Shamsuddin Iltutmish and Razia Sultan. He ascended the throne in 1246 at the age of 13. He was a weak and incompetent ruler and was dominated by his nobles. He died in 1266 while playing chaugan (polo).
Qutbuddin Aibak was the founder of the Mamluk dynasty of Delhi. He was a slave of Muhammad Ghori and rose to prominence in his service. He was appointed the governor of Punjab by Muhammad Ghori in 1192. After the death of Muhammad Ghori in 1206, Aibak declared himself the Sultan of Delhi. He ruled for four years and died in 1210.
Ghiyasuddin Balban was the second Sultan of the Mamluk dynasty of Delhi. He was a powerful and capable ruler who restored order and stability to the Delhi Sultanate. He ruled for 35 years from 1266 to 1287.
Shamsuddin Iltutmish was the third Sultan of the Mamluk dynasty of Delhi. He was a strong and capable ruler who expanded the Delhi Sultanate. He ruled for 26 years from 1211 to 1236.
Nasiruddin Mahmud was the fourth Sultan of the Mamluk dynasty of Delhi. He was a weak and incompetent ruler who was dominated by his nobles. He ruled for 20 years from 1246 to 1266.